/*
 *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

package org.webrtc;

import static java.lang.Math.abs;

import android.graphics.ImageFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

@SuppressWarnings("deprecation")
public class CameraEnumerationAndroid {
	private final static String TAG = "CameraEnumerationAndroid";

	static final ArrayList<Size> COMMON_RESOLUTIONS = new ArrayList<Size>(Arrays.asList(
			// 0, Unknown resolution
			new Size(160, 120), // 1, QQVGA
			new Size(240, 160), // 2, HQVGA
			new Size(320, 240), // 3, QVGA
			new Size(400, 240), // 4, WQVGA
			new Size(480, 320), // 5, HVGA
			new Size(640, 360), // 6, nHD
			new Size(640, 480), // 7, VGA
			new Size(768, 480), // 8, WVGA
			new Size(854, 480), // 9, FWVGA
			new Size(800, 600), // 10, SVGA
			new Size(960, 540), // 11, qHD
			new Size(960, 640), // 12, DVGA
			new Size(1024, 576), // 13, WSVGA
			new Size(1024, 600), // 14, WVSGA
			new Size(1280, 720), // 15, HD
			new Size(1280, 1024), // 16, SXGA
			new Size(1920, 1080), // 17, Full HD
			new Size(1920, 1440), // 18, Full HD 4:3
			new Size(2560, 1440), // 19, QHD
			new Size(3840, 2160) // 20, UHD
	));

	public static class CaptureFormat {
		// Class to represent a framerate range. The framerate varies because of lightning conditions.
		// The values are multiplied by 1000, so 1000 represents one frame per second.
		public static class FramerateRange {
			public int min;
			public int max;

			public FramerateRange(int min, int max) {
				this.min = min;
				this.max = max;
			}

			@Override
			public String toString() {
				return "[" + (min / 1000.0f) + ":" + (max / 1000.0f) + "]";
			}

			@Override
			public boolean equals(Object other) {
				if (!(other instanceof FramerateRange)) {
					return false;
				}
				final FramerateRange otherFramerate = (FramerateRange) other;
				return min == otherFramerate.min && max == otherFramerate.max;
			}

			@Override
			public int hashCode() {
				// Use prime close to 2^16 to avoid collisions for normal values less than 2^16.
				return 1 + 65537 * min + max;
			}
		}

		public final int width;
		public final int height;
		public final FramerateRange framerate;

		// TODO(hbos): If VideoCapturer.startCapture is updated to support other image formats then this
		// needs to be updated and VideoCapturer.getSupportedFormats need to return CaptureFormats of
		// all imageFormats.
		public final int imageFormat = ImageFormat.NV21;

		public CaptureFormat(int width, int height, int minFramerate, int maxFramerate) {
			this.width = width;
			this.height = height;
			this.framerate = new FramerateRange(minFramerate, maxFramerate);
		}

		public CaptureFormat(int width, int height, FramerateRange framerate) {
			this.width = width;
			this.height = height;
			this.framerate = framerate;
		}

		// Calculates the frame size of this capture format.
		public int frameSize() {
			return frameSize(width, height, imageFormat);
		}

		// Calculates the frame size of the specified image format. Currently only
		// supporting ImageFormat.NV21.
		// The size is width * height * number of bytes per pixel.
		// http://developer.android.com/reference/android/hardware/Camera.html#addCallbackBuffer(byte[])
		public static int frameSize(int width, int height, int imageFormat) {
			if (imageFormat != ImageFormat.NV21) {
				throw new UnsupportedOperationException("Don't know how to calculate "
						+ "the frame size of non-NV21 image formats.");
			}
			return (width * height * ImageFormat.getBitsPerPixel(imageFormat)) / 8;
		}

		@Override
		public String toString() {
			return width + "x" + height + "@" + framerate;
		}

		@Override
		public boolean equals(Object other) {
			if (!(other instanceof CaptureFormat)) {
				return false;
			}
			final CaptureFormat otherFormat = (CaptureFormat) other;
			return width == otherFormat.width && height == otherFormat.height
					&& framerate.equals(otherFormat.framerate);
		}

		@Override
		public int hashCode() {
			return 1 + (width * 65497 + height) * 251 + framerate.hashCode();
		}
	}

	// Helper class for finding the closest supported format for the two functions below. It creates a
	// comparator based on the difference to some requested parameters, where the element with the
	// minimum difference is the element that is closest to the requested parameters.
	private static abstract class ClosestComparator<T> implements Comparator<T> {
		// Difference between supported and requested parameter.
		abstract int diff(T supportedParameter);

		@Override
		public int compare(T t1, T t2) {
			return diff(t1) - diff(t2);
		}
	}

	// Prefer a fps range with an upper bound close to |framerate|. Also prefer a fps range with a low
	// lower bound, to allow the framerate to fluctuate based on lightning conditions.
	public static CaptureFormat.FramerateRange getClosestSupportedFramerateRange(
			List<CaptureFormat.FramerateRange> supportedFramerates, final int requestedFps) {
		return Collections.min(
				supportedFramerates, new ClosestComparator<CaptureFormat.FramerateRange>() {
					// Progressive penalty if the upper bound is further away than |MAX_FPS_DIFF_THRESHOLD|
					// from requested.
					private static final int MAX_FPS_DIFF_THRESHOLD = 5000;
					private static final int MAX_FPS_LOW_DIFF_WEIGHT = 1;
					private static final int MAX_FPS_HIGH_DIFF_WEIGHT = 3;

					// Progressive penalty if the lower bound is bigger than |MIN_FPS_THRESHOLD|.
					private static final int MIN_FPS_THRESHOLD = 8000;
					private static final int MIN_FPS_LOW_VALUE_WEIGHT = 1;
					private static final int MIN_FPS_HIGH_VALUE_WEIGHT = 4;

					// Use one weight for small |value| less than |threshold|, and another weight above.
					private int progressivePenalty(int value, int threshold, int lowWeight, int highWeight) {
						return (value < threshold) ? value * lowWeight
								: threshold * lowWeight + (value - threshold) * highWeight;
					}

					@Override
					int diff(CaptureFormat.FramerateRange range) {
						final int minFpsError = progressivePenalty(
								range.min, MIN_FPS_THRESHOLD, MIN_FPS_LOW_VALUE_WEIGHT, MIN_FPS_HIGH_VALUE_WEIGHT);
						final int maxFpsError = progressivePenalty(Math.abs(requestedFps * 1000 - range.max),
								MAX_FPS_DIFF_THRESHOLD, MAX_FPS_LOW_DIFF_WEIGHT, MAX_FPS_HIGH_DIFF_WEIGHT);
						return minFpsError + maxFpsError;
					}
				});
	}

	public static Size getClosestSupportedSize(
			List<Size> supportedSizes, final int requestedWidth, final int requestedHeight) {
		return Collections.min(supportedSizes, new ClosestComparator<Size>() {
			@Override
			int diff(Size size) {
				return abs(requestedWidth - size.width) + abs(requestedHeight - size.height);
			}
		});
	}

	// Helper method for camera classes.
	static void reportCameraResolution(Histogram histogram, Size resolution) {
		int index = COMMON_RESOLUTIONS.indexOf(resolution);
		// 0 is reserved for unknown resolution, so add 1.
		// indexOf returns -1 for unknown resolutions so it becomes 0 automatically.
		histogram.addSample(index + 1);
	}
}
